It may be difficult in some situations, e.g., on an oscilloscope, to observe and record a fault of an incoming signal where the cause and effect may be separated by significant periods of time. Various techniques have been attempted to address this problem, all of which have been without success. Attempts to increase the memory size enough to capture the event are often unsuccessful because of the vast amounts of data that are collected at maximum sample rates. A separation of cause and effect greater than 10 seconds is common, which would require an unpractical amount of memory. Further, even when there is enough memory available to capture the events, the amount of data to be processed may itself be unpractical to process in a reasonable amount of time, given the number of sample records that are generated in such a situation.
Attempts to decrease the sample rate of an oscilloscope to capture a longer time period of data have also been unsuccessful because the sample rate is reduced below the amount that is needed to observe the problem. This is exacerbated when the user may not even know what bandwidth he or she will need until the signals in question are observed. Further, the user may have a narrow glitch on a certain signal that is not recognized at a lower sample rate. Attempts to store blocks of samples around multiple trigger events have also largely failed because not all of the important events occur near a defined trigger and may instead occur at other times.